Waste disintegrator rotor and ring assembly

ABSTRACT

There is disclosed in this application a grinding rotor. The rotor comprises alternate layers of epoxy resin and abrasive grit and is reinforced with metal wire and fiberglass strands. The particular embodiment of the grinding rotor disclosed herein is adapted for use with waste disintegrators and is circumferentially surrounded by a ring which is also made of alternate layers of epoxy resin and abrasive grit. Reinforcing fiberglass strands are embedded in the ring to add rigidity.

United States Patent [1 1 Knox-et al.

[ WASTE DISINTEGRATOR ROTOR AND RING ASSEMBLY [75] Inventors: Raymond E. Knox, Dunedin; Roger W. Teague, Largo, both of Fla.

[73] Assignee: General Signal Corporation,

Rochester, NY.

221 Filed: Oct. 1, 1971 21 App]. No.: 185,795

[52] US. Cl 241/46 R, 51/206 NF, 241/296 [51] Int. Cl. B02c 18/40, 824d 7/04 [58] Field of Search 241/91, 92, 93, 291,

241/293, 296, 46 R, 46 A, 46 B; 51/206 R, 206 NF, 207, 209 R [56] References Cited UNITED STATES PATENTS 3,576,090 4/1971 Shoemaker 51/209 R 2,814,918 12/1957 Erickson 51/206 NF 11/1938 Scheel, Jr. 51/206 NF [451 July 17,1973

3,141,271 7/1964 Fischer et a1. 51/209 R 228,257 6/1880 Hart 51/206 NF 2,643,494 6/1953 Erickson.... 51/206 NF 2,745,224 5/1956 Ericks0n.... 51/207 X 2,826,016 3/1958 Hurst 51/206 NF 3,540,163 11/1970 Shoemaker 51/209 R Primary Examiner-Granville Y. Custer, Jr. AlmrneyJeffrey S. Mednick et al.

[57] ABSTRACT There is disclosed in this application a grinding rotor. The rotor comprises alternate layers of epoxy resin and abrasive grit and is reinforced with metal wire and fiberglass strands. The particular embodiment of the grinding rotor disclosed herein is adapted for use with waste disintegrators and is circumferentially surrounded by a ring which is also made of alternate layers of epoxy resin and abrasive grit. Reinforcing fiberglass strands are embedded in the ring to add rigidity.

7 Claims, 5 Drawing Figures Patented July 17, 1973 2 Sheets-Sheet 1 FIG. 1

FIG. 3

Patented July 17, 1973 3,746,266

2 Sheets-Sheet 2 F FIG. 4

FIG. 5

WASTE DISINTEGRATOR ROTOR AND RING ASSEMBLY BACKGROUND OF INVENTION This invention relates to a grinding rotor and, more particularly, relates to a grinding rotor adapted to be used in a waste disintegrator.

Waste disintegrators of the type used to grind solid particles in waste from commercial, industrial and agricultural facilities should be rugged, inexpensive and maintenance free. To accomplish the enumerated objectives, it has been proposed to provide a grinding rotor, one face of which includes an abrasive grit and which has openings extending axially through its face to allow the passage of liquids and ground solids. The rotor is mounted concentrically within and slightly spaced from a ring member to allow the passage of liquid and so that the edge of the rotor may also grind solid particles passing between the edge of the wheel and the ring. With this construction it is possible to provide relatively small solid particles since the size of the particles can be easily controlled by the size of the openings and the speed of rotation of the rotor.

In addition to the above enumerated objectives that a waste disintegrator must satisfy, there is imposed the additional requirement that the entire mechanism be corrosion resistant since, in use, the disintegrators are located in a sewer pipe. In an effort to satisfy this additional requirement and to keep the cost of the grinding mechanism relatively low, rotors and their associated rings have been made by molding epoxy resin and silicon carbide grit. These grinding wheels and rings, however, have been subject to cracking during installation of the rotor and ring in the disintegrator housing and the rotor has also been subject to cracking due to the stresses caused by the relatively high rotational speed to which it is subjected.

It is an object of this invention, therefore, to provide a waste disintegrator that includes a durable, maintenance free and inexpensive rotor and ring assembly.-

It is another object of this invention to provide a rotor and a ring that is easy and inexpensive to make.

These and other objects of this invention are accomplished by providing a grinding rotor made of alternate layers of epoxy resin and silicon carbide grit and which is reinforced with metal wire and fiberglass strands. The rotor may be used in a waste disintegrator and mounted so that it is concentrically surrounded by a ring which is also made of alternate layers of epoxy resin and silicon carbide grit and which is reinforced by fiberglass strands. When used in a waste disintegrator, one face of the rotor is formed by the grit and performs the grinding function and openings extend through the face portions to allow the passage of liquid and ground solids.

More specifically, the rotor may include circumferential wire and fiberglass strands and also laterally extending metal wires fonning a criss-cross pattern across the face of the rotor. In addition, first and second bundles of fiberglass strands may extend laterally throughout the face of the rotor in a serpentine configuration and should extend at generally right angles to each other.

For a better understanding of the invention, reference may be made to the following description ofa preferred embodiment, taken in conjunction with the Figures of the accompanying drawings, in which:

FIG. 1 is a schematic plan view of a waste disintegrator including a rotor and ring in accordance with this invention;

FIG. 2 is an exploded perspective view illustrating the method of making a grinding rotor in accordance with this invention;

FIG. 3 is a cross-sectional view of a grinding rotor made in accordance with this invention;

FIG. 4 is an exploded perspective view illustrating the method of making the ring in accordance with this invention;

FIG. 5 is a side view partly in section and having portions broken away for the sake of clarity of a ring made in accordance with this invention.

Referring to FIG. 1, there is shown a waste disintegrator 10 carried in a sewage pipe P in which waste materials flow in the direction of arrow A. Waste disintegrator 10 includes a suitable motor 12 which drives a grinding rotor 14 to grind solids in the waste material and reduce them to a suitable size. Motor 12 may be either electric or hydraulic, but since in use the motor is immersed in liquid the use of a hydraulic motor is preferred. Surrounding rotor 14 and spaced slightly from the periphery thereof is a ring member 16 which is carried by housing 18 which generally includes a centering mechanism for holding waste disintegrator 10 in pipe P. By spacing ring 16 from rotor 14 liquid can flow around the periphery of the rotor and some small solids may be ground by the periphery of the grinding wheel. The face of rotor 14 adjacent the inlet side of housing 18 is formed with an abrasive material which grinds solid particles in the waste and a plurality of apertures 20 extend through and between the faces of the rotor to allow the passage of liquid and the ground solid particles. It should also be noted that housing 18 does not engage the upper surface of pipe P and provides an emergency overflow for liquid in the event that the flow of waste should become excessive.

Referring now to FIG. 2, the method of making rotor 14 will now be explained. There is first provided a suitable mold 22, either urethane, wax or any other suitable type, in which is formed a central cavity 24 corresponding in size to the desired size of the rotor. Projecting upwardly-from the mold are a plurality of nubs 26 corresponding in location and size to the desired location and size of apertures 20 in the rotor. It should be understood, of course, that the actual pattern formed by apertures 20 can vary, but for purposes of clarity and simplicity nubs 26 are shown as forming generally aligned rows and columns intersecting at generally right angles. One of the nubs 27, however, is centrally located in cavity 24 and forms the opening through which the drive shaft of motor 12 projects.

After mold 22 has been thoroughly cleaned, a stainless steel wire 28 is placed adjacent the periphery of the mold so that it extends around the circumference of cavity 24. Wire 28 need not be of stainless steel, but could be made from a variety of other metals which are preferably corrosion resistant. If the length of wire 28 is longer than the circumference of the mold, the ends of the wire should be interlooped. Thereafter, a plurality of preferably stainless steel wires 30 are placed in cavity 24 so that one wire is located between adjacent rows of nubs and a second plurality of preferably stainless steel wires 32 are placed between adjacent columns of nubs so that one wire is located between adjacent columns of nubs. Wires 30 and 32, in plan view,

intersect each other and form a generally criss-cross pattern extending laterally across the bottom of the mold. It should be noted that wires 30 and 32 also need not be of stainless steel, but could be made from a variety of other metals which are preferably corrosion resistant.

A thin layer of epoxy resin 34 is now poured into the mold and the bottom of the mold is uniformly coated so that wires 28, 30 and 32 are raised from the bottom of cavity 24 and are embedded in the epoxy resin. It should be noted that various commercially available epoxy resins may be utilized and that one preferred epoxy resin includes shell 828 resin and a polyamide hardener. Thereafter, a layer of abrasive grit 36, preferably silicon carbide, is placed over top of the epoxy resin and is levelled to a generally uniform depth.

After the layer of grit has been levelled, a bundle 38 of fiberglass strands, that is, silicon glass in fiber form, is placed adjacent the periphery of mold 22 so that it extends around the circumference of cavity 24. Thereafter, a bundle 40 of fiberglass strands is placed between adjacent rows of nubs 26 so as to form a continuous fiberglass bundle extending throughout the area of cavity 24 in a serpentine configuration. Another bundle 42 of fiberglass strands is placed between adjacent columns of nubs 26 so as to form a continuous fiberglass bundle extending throughout the area of cavity 24 in a serpentine configuration. It should be clear that bundles 40 and 42 intersect each other at spaced points between the nubs and that the angle of intersection is approximately 90, but can vary depending upon the pattern formed by the nubs.

More epoxy resin 44 is now poured into the mold and should be placed so that bundles 38, 40 and 42 of fiberglass are completely embedded in the resin. The epoxy resin is levelled and a mounting disc 48 is now placed over center nub 27 of the mold so as to form a mounting aperture for securing the finished grinding rotor to the drive shaft of motor 12. Thereafter, another layer 50 of silicon carbide grit is placed over the surface of the epoxy resin excluding the area of mounting disc 48 and is also levelled to a generally uniform depth.

The mold is now allowed to set for a predetermined period of time until the epoxy resin hardens. Curing can be accomplished at room temperatures in from about 24 to 48 hours, or can be accomplished in the presence of heat depending upon the specific epoxy resin used. After the resin has been hardened, grinding rotor 14 is removed from the mold and the openings 20 and the periphery of the grinding rotor is cleaned.

Referring to FIG. 3, finished grinding rotor 14 is illustrated in cross-section and comprises alternate layers of epoxy resin 34 and 44 and silicon carbide grit 36 and 50. One face of the grinding rotor is comprised of epoxy resin 34 and the other face is comprised of abrasive grit 50 and provides the working or grinding face of the rotor. Wire 28 and fiberglass bundle 38 are carried in layers of epoxy resin 34 and 44, respectively, and provide rigidity to the periphery of rotor 14. Lateral reinforcement for grinding wheel 14 is provided by the individual strips of wire 30 and 32 carried in epoxy resin layer 34 and also by the bundles 40 and 42 of fiberglass strands which are carried in epoxy resin layer 44. It should be noted that wires 32 and fiberglass bundle 42 are not shown in FIG. 3, but that they extend generally across the rotor at an angle to wires 32 and fiberglass bundles 40, respectively.

Referring now to FIG. 4 the method of making ring member 16 will now ,be described. There is provided a suitable mold 52, either urethane, wax or any other suitable type, formed with an outer peripheral wall 54 and a central projection 56 so that an annular cavity 58 corresponding to the desired size of ring member 16 is provided. Extending radially through wall 54 are a plurality of openings 57 which receive mounting inserts 59 by which ring 16 is secured to housing 18 of the waste disintegrator.

After mold 52 has been cleaned, epoxy resin 60 is poured into cavity 58 and is levelled to form a relatively thin layer of resin. Thereafter, a bundle 62 of fiberglass strands is placed throughout the circumference of annular cavity 58 and is embedded in the epoxy resin 60. Now, abrasive grit 64, preferably silicon carbide, is placed in the mold and is also levelled to form a relatively thin layer. Mounting inserts 59 may now be inserted into openings 57 in wall 54. Thereafter, more epoxy resin 66 is poured into the mold to form a thin layer which should cover mounting inserts 59 and is followed by more grit 68 which, in turn, is followed by still more epoxy resin 70. All of the resin and grit is formed into relatively thin layers. The mold is now allowed to set for a predetermined period of time to allow the epoxy resin to cure in a manner similar to mold 22 when forming rotor 14. It should be noted that more fiberglass bundles could be embedded in epoxy resin layers 66 and 70 if desired. After the epoxy resin has hardened, ring 16 is removed from the mold and cleaned.

As seen in FIG. 5, ring 16 comprises layers of epoxy resin 60, grit 64, epoxy resin 66, grit 66 and epoxy resin 70. Fiberglass bundle 62 is carried in layer 60 epoxy resin and mounting inserts 59 are also carried in a layer of epoxy resin. Mounting inserts 59 may be of any suitable type and are illustrated as internally threaded sleeves.

It should be clear that both rotor 14 and ring member 16 are durable, inexpensive and easy to make. It should also be clear that a waste disintegrator utilizing rotor and ring members in accordance with this invention are durable, inexpensive and maintenance free mechanisms. Finally, it should be clear that the rotor, ring and methods of manufacture described herein may also be utilized with grinding mechanisms other than waste disintegrators.

While in the foregoing there has been described a preferred embodiment of the invention, various modifications may become apparent to those skilled in the art to which this invention relates. Accordingly, all such modifications are included within the intended scope of the invention as defined by the following claims:

What is claimed is:

l. A grinding rotor comprising alternate layers of epoxy resin and abrasive grit and reinforcing means imbedded in at least some of said layers of epoxy resin, said reinforcing means comprising metal wire and bundles of fiberglass strands.

2. A grinding rotor in accordance with claim I wherein said reinforcing means extends circumferentially adjacent the periphery of said rotor.

3. A grinding rotor in accordance with claim 1 wherein said reinforcing means extends across the face area of said rotor.

4. A grinding rotor in accordance with claim 3 wherein said reinforcing means includes a first group of metal wires extending generally parallel to each other in a first direction and a second group of metal wires extending generally parallel to each other in a second direction, wires of said first and second group intersecting each other to form a criss-cross configuration.

5. A grinding rotor in accordance with claim 3 wherein said reinforcing means includes a first bundle of fiberglass strands arranged in a serpentine configuration and a second bundle of fiberglass strands also arranged in a serpentine configuration such that the first and second bundles intersect each other at spaced points.

6. A grinding rotor in accordance with claim 1 wherein one face of said rotor is formed by a layer of grit and wherein a plurality of openings extend from said one face through to the other face of said rotor.

7. A waste disintegrator comprising a motor having a drive shaft carrying a grinding rotor, said grinding rotor comprising alternate layers of epoxy resin and abrasive grit and having a plurality of holes extending through the face portions thereof, some of said layers of epoxy resin including reinforcing means extending circumferentially and laterally therein, said rotor being concentric with and spaced from a ring member, said ring member comprising alternate layers of epoxy resin and grit and having reinforcing means extending circumferentially in at least some of some layers of epoxy resin. 

2. A grinding rotor in accordance with claim 1 wherein said reinforcing means extends circumferentially adjacent the periphery of said rotor.
 3. A grinding rotor in accordance with claim 1 wherein said reinforcing means extends across the face area of said rotor.
 4. A grinding rotor in accordance with claim 3 wherein said reinforcing means includes a first group of metal wires extending generally parallel to each other in a first direction and a second group of metal wires extending generally parallel to each other in a second direction, wires of said first and second group intersecting each other to form a criss-cross configuration.
 5. A grinding rotor in accordance with claim 3 wherein said reinforcing means includes a first bundle of fiberglass strands arranged in a serpentine configuration and a second bundle of fiberglass strands also arranged in a serpentine configuration such that the first and second bundles intersect each other at spaced points.
 6. A grinding rotor in accordance with claim 1 wherein one face of said rotor is formed by a layer of grit and wherein a plurality of openings extend from said one face through to the other face of said rotor.
 7. A waste disintegrator comprising a motor having a drive shaft carrying a grinding rotor, said grindiNg rotor comprising alternate layers of epoxy resin and abrasive grit and having a plurality of holes extending through the face portions thereof, some of said layers of epoxy resin including reinforcing means extending circumferentially and laterally therein, said rotor being concentric with and spaced from a ring member, said ring member comprising alternate layers of epoxy resin and grit and having reinforcing means extending circumferentially in at least some of some layers of epoxy resin. 